First picture it as one large rectangle with coordinates (-5, 0), (3,0), (-5-8), and (3,-8). That would make the rectangle 8X8 or 64
You then have to subtract the area of all the little triangles that are formed.
There are 4 triangles that are created if you make a large rectangle.
A=1/2bh
1: 7.5
2: 5
3: 5
4: 3
Subtract all those areas from the larger rectangle
64-7.5-5-5-3 = 43.5